This application relates to ultrasonic imaging catheters for medical use. More particularly, but not exclusively, it relates to intravascular catheters having a high frequency ultrasound imaging array that is capable of providing high quality, real-time, forward looking images. Alternatively or in addition, this application relates to catheters that incorporate “see-through” ablation electrodes in front of an ultrasound imaging array so as to facilitate image guided therapy inside a body lumen.
Intravascular ultrasound (IVUS) has been successfully implemented as a visualization tool to assist in the diagnosis and treatment of vascular diseases. (see e.g. Intracoronary Ultrasound, by Gary S. Mintz, MD, Taylor & Francis, 1995). However, existing intravascular ultrasound imaging devices designed for use in small lumens (e.g. coronary blood vessels) have either been unable to image in the forward direction or produced images of relatively poor quality. Furthermore, even though the addition of therapeutic ablation functionality into an ultrasound imaging catheter has generally been proposed, commercially available IVUS catheters lack any such therapeutic functionality. Accordingly, there is a need for intravascular devices having improved imaging capabilities and there is also a need for intravascular devices that successful integrate high quality imaging with the provision of ablation therapy. The present application provides systems and techniques for addressing one or both of those needs.
Particular catheters are described herein for use in treating obstructions in partially or totally occluded vessels, for example in peripheral or coronary arteries. These catheters combine miniature high frequency ultrasonic imaging arrays with “see through” RF electrodes such that the operator may enjoy substantially unobstructed direct visualization of the area undergoing treatment. In a preferred form, both the electrodes and the array are forward facing, and the catheter may be used to tunnel through arterial obstructions under real time visualization.